34 lines
1.4 KiB
Markdown
34 lines
1.4 KiB
Markdown
# Hello, JavaScript!
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The programs in JavaScript are called *scripts*. They can be embedded right into HTML using `<script>` tag and run automatically as the page loads.
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For example, this HTML-page shows the "Hello" message:
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```html run
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<!doctype html>
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<script>
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alert("Hello, world!");
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</script>
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```
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JavaScript can execute not only in a browser, but also on a server, or actually on any device that has a special program called [the JavaScript engine](https://en.wikipedia.org/wiki/JavaScript_engine).
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Browsers have built-in JavaScript engines, so they can run scripts.
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We can also run scripts using [Node.js](https://nodejs.org), it's commonly used to build server-side applications.
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Depending on the environment, JavaScript may provide platform-specific functionality.
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- In a web browser, JavaScript can manipulate the web-page, send network requests, show messages and so on.
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- In node.js we can use JavaScript to run a web-server, read and write arbitrary files.
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- ...And so on.
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Technically, even a coffee machine can include its own JavaScript engine, to allow programming of coffee recipes.
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**In this tutorial we concentrate on the "core JavaScript", that's the same everywhere.**
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We'll try to keep browser-specific notes at minimum. After you learn the core, you can go in any direction: browsers, frameworks, servers and so on.
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Turn the page to start learning JavaScript!
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